Heated furnace with heat recirculating means



March 6, W34. T, LYDON HEATED FURNACE WITH HEAT RECIRCULATING MEANS Filed Deo. 6, 1929 2 Sheets-Sheet l y arch 3934-.. T LYDON HEATED FURNACE WITH HEAT RECIRCULATING MEANS Filed Dec. 6, 1929 2 Sheets-Sheet 2 www.

m R mdf @um Nimwj 9 w IM .l m Hw Nm? 5% Patented Mar. 6, 1934 UNl'li STATES FTET OFFICE HEATED FURNACE WTH HEAT RECIB-CULATING MEANS 14 Claims.

This invention'relates to improvements in drying ovens, and it consists in the novel features, which are hereinafter described.

One of the objects of my improvement is to provide a perfected process and a drying oven, in which the air thereinis maintained at a high degree of uniform temperature throughout the oven space.

Another object of my invention is to provide a perfected drying oven, in which the gases of combustion are excluded from the drying space, insuring the apparatus against explosions of inflammable vapors, by prevention of explosive mixtures and preventing formation of gas pockets, which may be produced by the drying of sundry articles.

A still other object of my invention is to maintain the heating means, or parts radiating heat in the drying oven at a uniform and relatively n low temperature.

Another object of my invention is to maintain an internal air-circulation and agitation in my said perfected drying oven with the air being maintained at relatively low pressures within the -5 oven.

A further object of my invention is to provide an exhaust outlet and a damper for controlling the same, for intermittently discharging the air,

r circulated through my perfected oven, which C may be mixed with the vapors given off by sundry articles during the process of drying, to prevent explosions or other undesirable chemical reactions by said vapors. v

A further object is to admix the vapors with fresh air, and to this end means are provided to discharge such vapors and replace same with induced fresh air to obviate inammable or explosive mixtures.

Finally, as will hereinafter be ascertained, 4G means are provided herein, in one form, whereby incoming, ceol atmospheric air and the contained heated air within the oven, are continually brought into contact with the heated gases, without intermingling therewith thus providing for a rapid heat transfer from the isolated heating gases to the air supply and the air within the oven.

A still other object of my invention is to have the fan blower of my air circulating means placed interiorly of the drying oven, thereby permitting wider and shorter air duets to be employed, and thereby eliminating losses of heat and of power.

Another object of my invention is to increase the eiciency of the apparatus as a whole and to reduce the consumption of power used for circulating air through my drying oven.

Other objects and advantages will hereinafter appear.

I attain these objects by the drying oven and the appurtenances thereof, two forms of which are shown in the drawings or by any mechanical equivalents or obvious modifications of the same.

In the drawings,

Fig. l is a longitudinal vertical section of one form of my drying oven on the broken line 1 1-1-1 of Fig. 2, looking in the direction of the arrows and showing sundry parts in elevation;

Fig. 2 is a horizontal sectional top View on the line 2 2 of Fig. 1, showing sundry parts in plan view;

Fig. 3 is a fragmentary detail View partly in vertical section on the line 3 3 of Fig. 2 and 75 partly in end elevation of the sliding plates, which are hereinafter described, looking from left to right in Fig. 2 and drawn to a larger scale than Figs. 1 and 2;

Fig. 4 is a longitudinal vertical section of an- 80 other form of my drying oven on the line 4 4 of Fig. 5, looking in the direction of the arrows and showing sundry parts in elevation;

Fig. 5 is a transverse vertical section of my drying oven on the line 5 5 of Fig. 4, looking in the 85 direction of the arrows and showing sundry parts in elevation;

Fig. 6 is a .fragmentary horizontal sectional top View on the line 6 6 of Fig. 4;

Fig. 7 is a fragmentary detail bottom plan View 90 of one of the sliding plates, shown in Fig. 3;

Fig. 8 is a fragmentary detail view in perspective of the air inlet part of the combustion flue in the form of my drying oven shown in Figs. 4 and 5.

Like characters of reference refer to like parts throughout the several views:

11 designates an outer metal casing, l2 an inner metal casing and 13 heat insulating material of the walls of the outer shell 14 of an electrically 100 heated drying oven shown in Figs. l and 2; the doors 15 of the oven consist of similar parts.

centrifugal fan or blower 16 is overhung interiorly of said shell 14 under the top 17 thereof, to revolve in a horizontal plane, and is secured to a vertical shaft 18, supported in suitable bearings 19 and 20; said shaft 18 has secured thereto at the upper end thereof a suitable source of power 21, which may be either a pulley or a directconnected motor, 110

Said fan 16 is enclosed by a casing 22, which has thereon at the exhaust thereof an outwardly diverging discharge passage 23, which is joined to a vertically disposed pressure nue or heater 24, extending along the right hand side of the shell 14, as seen in Figs. 1 and 2, from the front to the rear thereof.

An inlet casing 25 for said fan 16 communicates with the central part of said casing 22 at the lower end thereof and has thereon an outwardly diverging and inwardly converging intake pas sage 26, which is joined to a vertically disposed suction iiue or header 27, which extends along the left hand side of said shell 14, as seen in Figs. 1 and 2, from the front to the rear thereof.

The inner wall of each of said flues 24 and 27 has therein numerous apertures 28 and 29 respectively, for he egress of air from the pressure flue 24 into the drying space between said flues, forming the drying oven, and for the ingress of air from the said drying oven into the suction ue 27, thereby permitting the air to be circulated by said fan 16 through said oven transversely thereto, thereby maintaining a uniform temperature therein.

An electrical heater 30 is placed in said flue 27 and has its terminal wires 31 and 32 extend through said wall 11-12-13 to a suitable source of electric energy.

A truck or car 33, having thereon shelves 34, which are diagrammatically illustrated in Fig. 1, is employed to carry thereon articles, which are to be dried, and which are placed on said shelves 34; the doors 15 of said shell 1 4 are employed for admitting said truck or car 33 therethrough into the said oven and for removing said truck therethrough from said oven after the drying of said articles has been completed.

To remove or discharge the fumes or vapors resulting from the drying of said articles an outlet 35 is provided at the top of said passage 23 through the top 17 of the shell 14, to be controlled by a damper 36, which is hingedly connected to said passage 23 at 37 and may be controlled either manually or in any other suitable way.

The damper 36 may either be opened and closed at intervals, or it may be partly open all the time and the extent of its opening regulated.

To permit vapor mixed with air to escape from the oven through said outlet 35 by convection an inlet 38 for atmospheric air is provided at the foot of said shell 14, as shown in Fig. 1, to communicate with the lower end of said flue 27, thereby admitting atmospheric air to replace the mixture of air and vapor which escapes through said outlet 35.

The pressure of the air in said flue 27 is normally slightly below atmospheric pressure when said outlet 35 is open and at atmospheric pressure when said outlet 35 is closed.

When it is desired to reduce or vary the pressure in said flue 27 and to provide additional regulation of the flow of air through said oven, when said damper 35 is open, the admission of air through said inlet 38 may be varied and adjusted by means of a pair of perforated plates 39 and 40, shown as placed in the lower part of said flue 27, one of which plates, as 39, may be fixed in position and extend across said Ldue 27 from the front to the roar of said iiue 27, and the other plate 40 may be shorter and mounted to be slid under said plate 33 by means of a flange 4l at the front of said plate 43 and a feed screw 42, which threadedly passes through the casings 11 and 12 and a nut 42b therebetween at the front of said shell 14 and said screw has its inner end swivelled in said ila-nge 41; endwise motion of said screw 42 with relation to said flange 41 is prevented by means of a collar 43 at the inner end ci said screw 42 interiorly of said ange 4l and a collar 44 exteriorly thereof. The screw 42 is turned by means of a head 42a thereon. Set screws 45 are provided for said collars 43 and 44 on said screw 42.

When the plate 40 is moved from right to left in Fig. 3, the perforations 494 thereon are gradually brought into registration with the perforations 39a on said plate 39, thereby increasing the total area of the openings for the inlet of air into said ue 27, thereby bringing the pressure therein more nearly to that of the atmosphere, when said plate 40 is moved from left to right in Fig. 3 the total area of the said openings is reduced, thereby reducing the pressure in said flue 27.

In good practice the admission of air at the inlet 38 is never cut off entirely; neither is the egress of air through the outlet 35 entirely shut olf during the process of drying.

The pressure of the air in said iiue 24 is some what but not much higher than in said nue 27.

To humidify the overheated air in the drying oven water may be admitted to the interior of said shell 14 by means of a pipe 46, which is provided with a valve 46a and suitable regulating devices exteriorly of said shell 14, which are not shown, in the drawings.

In the form of my drying oven, which is shown in Figs. 4 and 5 heat is supplied by the combustion of a suitable gas or oil, in a burner 47, which is placed in a combustion flue 27e at the lower end of the suction ue 43-49- The major part of the suction nue in this type of my drying oven is divided into a number of adjacent alternate gas cells 48 and hot air cells 49.

The walls 50 between adjacent cells 48 and 49 conduct the heat from the former to the latter.

The gases of combustion from the flue at 27@- pass upwardly by convection over a baffle 50*L of refractory material, and through said cells 48. which open into a common upper flue 51, to be exhausted by means of an outlet at 52 at the top of said fine 51.

Convection of said gases is established by means of an inlet 53 admitting fresh air from the atmosphere at the foot of said combustion flue 27a, said inlet 53 is located at the front of said shell 14, as

shown in Figs. 4 and 5, and is bounded on the sides thereof by a frontward extension of the sides of said flue 27a at the foot thereof, as shown in Fig. 8, and at the top thereof by a horizontal flange at the front of said chamber 274.

The air cells 49 have thereon perforations or openings 54 on the inner side thereof and other perforations or openings 55 on the outer side thereof.

These perforations or openings 54 and 55 extend through the major part of the sides of said air cells 49; and said openings 55 are staggered with relation to said openings 54, as viewed in Fig. 5.

A port 56 at the upper end of the inner side of each of said cells 49 opens into the intake passage 26 of an inlet casing 25 of a fan 16; the discharge passage 23 of the fan casing 22 is joined to a pressure ue or header 24, which is similar to the hereinbefore described header for an electrically heated drying oven embodying my invention and has therein perforations or openings 28 on the inner side thereof communicating with the central space of the shell 14, forming the drying oven proper.

Circulation of the hot air in said cells 49 is maintained by said fan 16 as in the form of my drying oven, which is electrically heated, as hereinbefore described.

To discharge fumes and vapors from the drying oven an outlet 57 is provided at the top of said discharge passage 23, said outlet 57 extends through the upper end of the oven and the top 17 of said shell 14, and is controlled by a damper 36, which is hingedly connected at 58 to the top of said discharge passage 23, as shown in Fig. 4.

To permit fumes to be discharged through said outlet 57 atmospheric air is admitted to the drying oven through an inlet 59 which is provided at the left side of said shell 14, as seen in Fig. 4, near the foot thereof.

A baie plate 60 deects the air drawn in at 59 into a vertically disposed inlet air chamber 61, enclosed between the casing l2 of the left wall of said shell 14 in Fig. 4 and said cells 48-49; from the chamber 61 the air is drawn in by suction through said apertures 55 into said cells 49, from which it is drawn by suction through said ports 56 into the intake passage 26 of the inlet casing 25 of said fan 16.

The damper 36 is preferably partly open continually during the process of drying, although it may also be intermittently open, and the eX- tent of the opening thereof may be regulated either by hand or in any other desired manner.

A closure 62 is provided at the upper end of said chamber 6l, and a closure 63 at each side thereof, to prevent atmospheric air from being short-circuited into the drying oven.

Articles to be dried may be introduced on shelves 34 into the form of my drying oven shown in Figs. 4 and 5 in the same manner as in the modification thereof shown in Figs. l and 2.

Where such regulating devices are employed for the admission of air, the damper 36 may be omitted and the outlets 35 and 57 kept continually open, if desired.

Many other changes may be made in the modifications of my drying oven without departing from the main scope of my invention, and parts of my invention may be used Without other parts.

I do not therefore restrict myself to the details as shown in the drawings; but I intend to include also all mechanical equivalents and obvious modifications of the same within the scope of my invention.

I claim as my invention and desire to secure by Letters Patent:

l. In a drying oven, a shell enclosing the same, a suction flue and a pressure flue placed interiorly of said oven, said flues having therein openings for the ingress and egress of air therethrough, a fan disposed within said oven, a casing for enclosing the same, an intake passage for joining said suction flue to the inlet of said casing, an exhaust passage for joining said casing to said pressure ue, a means for actuating said fan thereby circulating air through said ues and said oven, an outlet to the exterior of said shell at the top of said exhaust passage for discharging therethrough vapors produced by drying, and an inlet for admitting air from the exterior of said shell to the foot of said oven to permit said discharge being effected mainly by convection.

2. In a drying oven, a shell enclosing the same, a suction flue and a pressure flue placed interiorly of said oven, said ues having therein openings for the ingress and egress of air therethrough, a fan disposed within said oven, a casing for enclosing the same, one or more passages for joining said casing to said ues, a means for actuating said fan thereby circulating air through said iiues and said oven, an outlet to the exterior of said shell for discharging therethrough vapors produced by drying, an inlet for admitting air from the exterior of said shell to the foot of said oven to permit said discharge being effected mainly by convection, and a means for regulating the discharge at said outlet.

3. In a drying oven, a shell enclosing the same, a suction iiue and. a pressure ue placed interiorly of said oven, said fiues having therein openings for the ingress and egress of air therethrough, a fan and a casing for enclosing the same both disposed within said oven, one or more passages for joining said casing to said flues, a means for actuating said fan thereby circulating air through said iiues and said oven, an outlet to the exterior of said shell for discharging therethrough vapors produced by drying, an inlet for admitting air from the exterior of said shell to the foot of said oven to permit said discharge being effected mainly by convection and a means for regulating the admission of air at said inlet.

4. In a drying oven, a shell enclosing the same, a suction flue and a pressure flue placed interiorly of said oven, said flues having therein openings for the ingress and egress of air therethrough, a fan and a casing for enclosing the same both disposed within said oven, one or more passages for joining said casing to said nues, a means for actuating said fan thereby circulating air through said dues and said oven, an outlet to the exterior of said shell for discharging therethrough vapors produced by drying, an inlet for admitting air from the exterior of said shell to the foot of said oven to permit said discharge being effected mainly by convection, a pair of apertured plates at said inlet, the apertures of one plate being adapted to register with the apertures of the other plate, and a means for varying the position of one plate with relation to the other thereby varying the extent of registration of said apertures and thereby regulating the admission of air at said inlet.

5. In a drying oven having insulating walls to dene its interior and having an inlet at its bottom for fresh air and an outlet through its top for used air; means above the top of said inlet for regulating the air now; means immediately above said regulator for heating the air; a suction flue enclosing the regulator and heater; a pressure f i flue remote from the suction fiue, the inner walls of said iiues having perforations for the passage of air; a casing located centrally of the oven and at the ceiling thereof; suction and pressure ducts connecting the casing to the respective suction and pressure fiues, said pressure duct communieating with the said used air outlet; means for controlling the air at said outlet, and a suction blower device revolubly mounted @within said casing.

6. In a drying oven having insulating walls to denne its interior, an air inlet in one side wall at the hoor line, an air damper at the top of said inlet, a heater just above said damper, a flue extending up the inner face of the said side wall and containing said damper and heater; a blower permanently xed to the ceiling of said oven; a casing enclosing said blower, a fdue disposed at the opposite side of the oven, said fiues having respective intake and discharge apertures in their opposed faces and flaring piped connections between the fines and blower casing, the horizontal plane of the intake connection being lower than the horizontal plane of the outlet.

7. In combination, a rectangular shell of heat insulating material having a non-vertical top wall; an axially vertical fan shaft passing vertically through the mid part of the said wall; separated alined bearings for said shaft exterior to the shell; a centrifugal fan fast on the shaft adjacent to said Wall and having horizontal blades in planes radial to said shaft, said blades having vertical end edges, whereby air drawn into the fan at the middle part, is thrown tangentially horizontally from the end edges; substantially upright ues on respectively opposite sides of interior of the shell adjacent to the side Walls thereof and extending substantially from top to bottom` and front to rear of said side walls; the walls of said ues nearest the center of the interior of the shell being provided substantially from top to bottom and front to rear with air passage openings; the lower part of the suction flue and adjacent portion of the shell being provided with an inlet passage; means forming a substantially horizontal discharge passage from the fan to the top of the pressure flue, said passage being free of obstruction along tangente of the tips of the fans to all parts of the upper end of the flue respectively, whereby currents from said tips are evenly distributed across the ue.

8. In combination, a shell having opposite walls and an intermediate wall; a centrifugal fan in the interior of said shell near, and axially substantially perpendicular to said intermediate wall; a casing around said fan having a side opening and curved side walls adjacent to the tips of the fan blades; suction and pressure flues on opposite sides of said interior near said opposite walls and extending substantially from top to bottom and front to rear thereof; said nues-being provided with passage openings toward the mid part of said interior and end openings extending from front to rear near said intermediate wall; passage means cooperating with said side opening and the end opening of the pressure flue to form an unobstructed discharge passage from the ian to the pressure iiue, comprising diverging walls extending substantially tangentially from tips of the blades to the adjacent corner portions respectively of the pressure-nue, thereby to avoid eddies in the passage means; and means forming a passage from the end opening of the suction nue to the intake of the fan casing.

9. In combination, a shell having opposite walls and an intermediate wall; a centrifugal fan in the interior of said shell near, and axially substantially perpendicular to said intermediate wall; a casing around said fan having a side opening and side walls adjacent to the tips of the fan blades; suction and pressure nues on opposite sides of said interior near said opposite walls and extending substantially from top to bottom and front to rear thereof; said lues being provided with passage openings toward the mid part of said interior; means cooperating with said side opening to form an unobstructed discharge passage from the fan to the pressure flue, comprising diverging walls extending substantially tangentially from tips or the blades to the adjacent corner portions respectively of the pressure-flue; and passage means forming an unobstructed passage from the interior of the suction flue to the intake of the casing and having converging side walls extending from the intake of the case to the corner portions of the suctionflue adjacent to one of said opposite Walls, thereby to avoid eddies in the passage means; said suction flue opening all the way across into said passage means.

10. In combination, a shell having opposite Walls and an intermediate wall; a centrifugal fan in the interior of said shell near, and substantially axially perpendicular to said intermediate wall; a casing around said fan having an intake opening and having a side opening and side walls adjacent to the tips of the fan blades; suction and pressure fiues on opposite sides of said interior near said opposite walls and extending substantially from top to bottom and front to rear thereof; said iiues being provided with passage openings toward the mid part of said interior; passage means cooperating with said side opening to form an unobstructed discharge passage from the fan to the pressure iiue; means forming a passage from the suction flue to the intake opening of the casing; said passage means being provided with an outlet opening from said passage means to the exterior of the shell; and a damper hinged within the passage means on the side remote from the fan and adjustably pointing toward the fan, to guide currents into the outlet passage.

il. In combination, a shell having side Walls and a substantially horizontal wall; an axially vertical centrifugal fan in the interior of said shell near said horizontal wall; a casing having a side opening and curved sides near the' fanblade tips; upright suction and pressure ues on opposite sides of said interior, extending substantially from top to bottom and front to rear thereof; said flues being provided with passage openings toward the mid part of said interior and end openings across the upper ends; means cooperating with said side opening and the end opening cf the pressure flue to form an unobstructed discharge passage from the fan to the upper part of the pressure flue, comprising a horizontal bottom wall, and side walls extending substantially horizontally tangentially from the blade tips to the front and rear pressure-flue walls respectively, whereby air is evenly distributed tangentially from said tips free of eddies, free of lateral gravity components, whereby even distribution is maintained; and means forming a passage from the suction flue to the intake of the casing and having converging side Walls extending from the front and rear suction-nue Walls to the intake case.

12. In combination, a shell having side Walls and a substantially horizontal wall; an axially vertical centrifugal fan in the interior of said shell near said horizontal Wall; a casing having a side opening and curved sides near the fan-blade tips; upright suction and pressure ues on opposite sides of said interior, extending substantially from top to bottom and front to rear thereof; said fiues being provided with intermediate passage openings toward the mid part of said interior and upper end openings extending across the upper ends; means cooperating with said opening to form an unobstructed discharge passage from the fan to the upper end opening of the pressure iiue; passage means forming a passage from the suction flue to the intake of the casing; and a heater in the suction flue; said casing, passage means and suction flue being spaced from the adjacent parts of the shell, and

the pressure ue being substantially in contact with the shell.

13. In combination, a shell having side Walls and a substantially horizontal wall; an axially vertical centrifugal fan in the interior of said shell near said horizontal Wall; a casing having a side opening and curved sides near the fanblade tips; upright suction and pressure ues on opposite sides of said interior, extending substantially from top to bottom and front to rear thereof; said ues being provided with passage openings toward the mid part of said interior; means cooperating With said opening to form an unobstructed discharge passage from the fan t0 the upper part of the pressure flue; means forming a passage from the suction flue to the intake of the casing; and upright spaced heater flues in said suction ue.

14. In combination, a shell having side Walls and a substantially horizontal Wall; an axially vertical centrifugal fan in the interior of said shell near said horizontal wall; a casing having a side opening and curved sides near the fanblade tips; upright suction and pressure flues on opposite sides of said interior, extending substantially from top to bottom and front to rear thereof said lues being provided with passage openings toward the mid part of said interior; passage means cooperating With said side opening to form an unobstructed discharge passage from the fan to the upper part of the pressure flue and having an outlet opening to the exterior of the shell; means forming a passage from the suction ue to the intake of the casing; the suction iiue having an inlet opening at its lower part; a heater in the lower part of the suction flue; and relatively slidable perforated plates across the suction iue above the heater and having openings registerable and closable as the plates relatively slide.

TIMOTHY LYDON. 

